Classroom management skills are evidence-based strategies used to maintain a positive and productive learning environment. Utilizing classroom management strategies has been proven effective; however, limited tools are available for assessing such skills and further assessment of the reliability and dependability of such measures is needed. The Direct Behavior Rating -- Classroom Management (DBR-CM) forms are measures for assessing classroom management and come in three forms: external rater (DBR-CM ER), self-report (DBR-CM SR), and student rater (DBR-CM ST). This study extended on the information obtained from the Cassidy (2018) study that examined the DBR-CM ER form. The study evaluated the inter-observer agreement among the DBR-CM ER and DBR-CM SR forms. Additionally, this study examined the variance contributing to the classroom management ratings for both the DBR-CM SR and DBR-CM ER forms. A fully crossed analytic design (p x d x m) with two facets, day (d: observations) and method (m: rater type), and person (p: teachers) as the object of measurement was created. A follow-up decision (D) study was conducted to assess the number of 10 minute observations required to conduct a reliable rating with the DBR-CM SR and DBR-CM ER forms. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]